<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/tools/testing/selftests/net/fib_nexthops.sh, branch linux-rolling-stable</title>
<subtitle>Hosts the 0x221E linux distro kernel.</subtitle>
<id>https://universe.0xinfinity.dev/distro/kernel/atom?h=linux-rolling-stable</id>
<link rel='self' href='https://universe.0xinfinity.dev/distro/kernel/atom?h=linux-rolling-stable'/>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/'/>
<updated>2025-12-30T09:39:22Z</updated>
<entry>
<title>selftests: fib_nexthops: Add test cases for error routes deletion</title>
<updated>2025-12-30T09:39:22Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2025-12-21T14:48:29Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=44741e9de29bff4911b045b961393c5d837f51ae'/>
<id>urn:sha1:44741e9de29bff4911b045b961393c5d837f51ae</id>
<content type='text'>
Add test cases that check that error routes (e.g., blackhole) are
deleted when their nexthop is deleted.

Output without "ipv4: Fix reference count leak when using error routes
with nexthop objects":

 # ./fib_nexthops.sh -t "ipv4_fcnal ipv6_fcnal"

 IPv4 functional
 ----------------------
 [...]
       WARNING: Unexpected route entry
 TEST: Error route removed on nexthop deletion                       [FAIL]

 IPv6
 ----------------------
 [...]
 TEST: Error route removed on nexthop deletion                       [ OK ]

 Tests passed:  20
 Tests failed:   1
 Tests skipped:  0

Output with "ipv4: Fix reference count leak when using error routes
with nexthop objects":

 # ./fib_nexthops.sh -t "ipv4_fcnal ipv6_fcnal"

 IPv4 functional
 ----------------------
 [...]
 TEST: Error route removed on nexthop deletion                       [ OK ]

 IPv6
 ----------------------
 [...]
 TEST: Error route removed on nexthop deletion                       [ OK ]

 Tests passed:  21
 Tests failed:   0
 Tests skipped:  0

Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/20251221144829.197694-2-idosch@nvidia.com
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</content>
</entry>
<entry>
<title>selftests: fib_nexthops: Add test cases for FDB status change</title>
<updated>2025-09-24T00:01:05Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2025-09-21T15:08:24Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=00af023d90f9087ed5a371302ab442ed5736c3b7'/>
<id>urn:sha1:00af023d90f9087ed5a371302ab442ed5736c3b7</id>
<content type='text'>
Add the following test cases for both IPv4 and IPv6:

* Can change from FDB nexthop to non-FDB nexthop and vice versa.
* Can change FDB nexthop address while in a group.
* Cannot change from FDB nexthop to non-FDB nexthop and vice versa while
  in a group.

Output without "nexthop: Forbid FDB status change while nexthop is in a
group":

 # ./fib_nexthops.sh -t "ipv6_fdb_grp_fcnal ipv4_fdb_grp_fcnal"

 IPv6 fdb groups functional
 --------------------------
 [...]
 TEST: Replace FDB nexthop to non-FDB nexthop                        [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop                        [ OK ]
 TEST: Replace FDB nexthop address while in a group                  [ OK ]
 TEST: Replace FDB nexthop to non-FDB nexthop while in a group       [FAIL]
 TEST: Replace non-FDB nexthop to FDB nexthop while in a group       [FAIL]
 [...]

 IPv4 fdb groups functional
 --------------------------
 [...]
 TEST: Replace FDB nexthop to non-FDB nexthop                        [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop                        [ OK ]
 TEST: Replace FDB nexthop address while in a group                  [ OK ]
 TEST: Replace FDB nexthop to non-FDB nexthop while in a group       [FAIL]
 TEST: Replace non-FDB nexthop to FDB nexthop while in a group       [FAIL]
 [...]

 Tests passed:  36
 Tests failed:   4
 Tests skipped:  0

Output with "nexthop: Forbid FDB status change while nexthop is in a
group":

 # ./fib_nexthops.sh -t "ipv6_fdb_grp_fcnal ipv4_fdb_grp_fcnal"

 IPv6 fdb groups functional
 --------------------------
 [...]
 TEST: Replace FDB nexthop to non-FDB nexthop                        [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop                        [ OK ]
 TEST: Replace FDB nexthop address while in a group                  [ OK ]
 TEST: Replace FDB nexthop to non-FDB nexthop while in a group       [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop while in a group       [ OK ]
 [...]

 IPv4 fdb groups functional
 --------------------------
 [...]
 TEST: Replace FDB nexthop to non-FDB nexthop                        [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop                        [ OK ]
 TEST: Replace FDB nexthop address while in a group                  [ OK ]
 TEST: Replace FDB nexthop to non-FDB nexthop while in a group       [ OK ]
 TEST: Replace non-FDB nexthop to FDB nexthop while in a group       [ OK ]
 [...]

 Tests passed:  40
 Tests failed:   0
 Tests skipped:  0

Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/20250921150824.149157-4-idosch@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>selftests: fib_nexthops: Fix creation of non-FDB nexthops</title>
<updated>2025-09-24T00:01:05Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2025-09-21T15:08:23Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=c29913109c70383cdf90b6fc792353e1009f24f5'/>
<id>urn:sha1:c29913109c70383cdf90b6fc792353e1009f24f5</id>
<content type='text'>
The test creates non-FDB nexthops without a nexthop device which leads
to the expected failure, but for the wrong reason:

 # ./fib_nexthops.sh -t "ipv6_fdb_grp_fcnal ipv4_fdb_grp_fcnal" -v

 IPv6 fdb groups functional
 --------------------------
 [...]
 COMMAND: ip -netns me-nRsN3E nexthop add id 63 via 2001:db8:91::4
 Error: Device attribute required for non-blackhole and non-fdb nexthops.
 COMMAND: ip -netns me-nRsN3E nexthop add id 64 via 2001:db8:91::5
 Error: Device attribute required for non-blackhole and non-fdb nexthops.
 COMMAND: ip -netns me-nRsN3E nexthop add id 103 group 63/64 fdb
 Error: Invalid nexthop id.
 TEST: Fdb Nexthop group with non-fdb nexthops                       [ OK ]
 [...]

 IPv4 fdb groups functional
 --------------------------
 [...]
 COMMAND: ip -netns me-nRsN3E nexthop add id 14 via 172.16.1.2
 Error: Device attribute required for non-blackhole and non-fdb nexthops.
 COMMAND: ip -netns me-nRsN3E nexthop add id 15 via 172.16.1.3
 Error: Device attribute required for non-blackhole and non-fdb nexthops.
 COMMAND: ip -netns me-nRsN3E nexthop add id 103 group 14/15 fdb
 Error: Invalid nexthop id.
 TEST: Fdb Nexthop group with non-fdb nexthops                       [ OK ]

 COMMAND: ip -netns me-nRsN3E nexthop add id 16 via 172.16.1.2 fdb
 COMMAND: ip -netns me-nRsN3E nexthop add id 17 via 172.16.1.3 fdb
 COMMAND: ip -netns me-nRsN3E nexthop add id 104 group 14/15
 Error: Invalid nexthop id.
 TEST: Non-Fdb Nexthop group with fdb nexthops                       [ OK ]
 [...]
 COMMAND: ip -netns me-0dlhyd ro add 172.16.0.0/22 nhid 15
 Error: Nexthop id does not exist.
 TEST: Route add with fdb nexthop                                    [ OK ]

In addition, as can be seen in the above output, a couple of IPv4 test
cases used the non-FDB nexthops (14 and 15) when they intended to use
the FDB nexthops (16 and 17). These test cases only passed because
failure was expected, but they failed for the wrong reason.

Fix the test to create the non-FDB nexthops with a nexthop device and
adjust the IPv4 test cases to use the FDB nexthops instead of the
non-FDB nexthops.

Output after the fix:

 # ./fib_nexthops.sh -t "ipv6_fdb_grp_fcnal ipv4_fdb_grp_fcnal" -v

 IPv6 fdb groups functional
 --------------------------
 [...]
 COMMAND: ip -netns me-lNzfHP nexthop add id 63 via 2001:db8:91::4 dev veth1
 COMMAND: ip -netns me-lNzfHP nexthop add id 64 via 2001:db8:91::5 dev veth1
 COMMAND: ip -netns me-lNzfHP nexthop add id 103 group 63/64 fdb
 Error: FDB nexthop group can only have fdb nexthops.
 TEST: Fdb Nexthop group with non-fdb nexthops                       [ OK ]
 [...]

 IPv4 fdb groups functional
 --------------------------
 [...]
 COMMAND: ip -netns me-lNzfHP nexthop add id 14 via 172.16.1.2 dev veth1
 COMMAND: ip -netns me-lNzfHP nexthop add id 15 via 172.16.1.3 dev veth1
 COMMAND: ip -netns me-lNzfHP nexthop add id 103 group 14/15 fdb
 Error: FDB nexthop group can only have fdb nexthops.
 TEST: Fdb Nexthop group with non-fdb nexthops                       [ OK ]

 COMMAND: ip -netns me-lNzfHP nexthop add id 16 via 172.16.1.2 fdb
 COMMAND: ip -netns me-lNzfHP nexthop add id 17 via 172.16.1.3 fdb
 COMMAND: ip -netns me-lNzfHP nexthop add id 104 group 16/17
 Error: Non FDB nexthop group cannot have fdb nexthops.
 TEST: Non-Fdb Nexthop group with fdb nexthops                       [ OK ]
 [...]
 COMMAND: ip -netns me-lNzfHP ro add 172.16.0.0/22 nhid 16
 Error: Route cannot point to a fdb nexthop.
 TEST: Route add with fdb nexthop                                    [ OK ]
 [...]
 Tests passed:  30
 Tests failed:   0
 Tests skipped:  0

Fixes: 0534c5489c11 ("selftests: net: add fdb nexthop tests")
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/20250921150824.149157-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>selftests: fib_nexthops: do not mark skipped tests as failed</title>
<updated>2025-02-22T00:23:29Z</updated>
<author>
<name>Hangbin Liu</name>
<email>liuhangbin@gmail.com</email>
</author>
<published>2025-02-20T08:53:26Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=465b210fdc653086fca34914c3a633efafb83e71'/>
<id>urn:sha1:465b210fdc653086fca34914c3a633efafb83e71</id>
<content type='text'>
The current test marks all unexpected return values as failed and sets ret
to 1. If a test is skipped, the entire test also returns 1, incorrectly
indicating failure.

To fix this, add a skipped variable and set ret to 4 if it was previously
0. Otherwise, keep ret set to 1.

Signed-off-by: Hangbin Liu &lt;liuhangbin@gmail.com&gt;
Link: https://patch.msgid.link/20250220085326.1512814-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>selftests: net: Fix few spelling mistakes</title>
<updated>2025-02-19T02:10:31Z</updated>
<author>
<name>Chandra Mohan Sundar</name>
<email>chandru.dav@gmail.com</email>
</author>
<published>2025-02-17T14:15:16Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=f29e41454b94e6e4f3cdf340947b61fd22950c96'/>
<id>urn:sha1:f29e41454b94e6e4f3cdf340947b61fd22950c96</id>
<content type='text'>
Fix few spelling mistakes in net selftests

Signed-off-by: Chandra Mohan Sundar &lt;chandru.dav@gmail.com&gt;
Reviewed-by: Petr Machata &lt;petrm@nvidia.com&gt;
Link: https://patch.msgid.link/20250217141520.81033-1-chandru.dav@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>selftests: fib_nexthops: Test 16-bit next hop weights</title>
<updated>2024-08-13T00:50:35Z</updated>
<author>
<name>Petr Machata</name>
<email>petrm@nvidia.com</email>
</author>
<published>2024-08-07T14:13:51Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=4b808f44733243f981ae04046ef93a65ecc631a9'/>
<id>urn:sha1:4b808f44733243f981ae04046ef93a65ecc631a9</id>
<content type='text'>
Add tests that attempt to create NH groups that use full 16 bits of NH
weight.

Signed-off-by: Petr Machata &lt;petrm@nvidia.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://patch.msgid.link/101cdd3f2bfd9511c9bec95f909d20ff56f70ba5.1723036486.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>nexthop: Fix out-of-bounds access during attribute validation</title>
<updated>2024-03-12T03:35:20Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2024-03-11T16:23:06Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=d8a21070b6e168d3800c2962a574f16020dd2951'/>
<id>urn:sha1:d8a21070b6e168d3800c2962a574f16020dd2951</id>
<content type='text'>
Passing a maximum attribute type to nlmsg_parse() that is larger than
the size of the passed policy will result in an out-of-bounds access [1]
when the attribute type is used as an index into the policy array.

Fix by setting the maximum attribute type according to the policy size,
as is already done for RTM_NEWNEXTHOP messages. Add a test case that
triggers the bug.

No regressions in fib nexthops tests:

 # ./fib_nexthops.sh
 [...]
 Tests passed: 236
 Tests failed:   0

[1]
BUG: KASAN: global-out-of-bounds in __nla_validate_parse+0x1e53/0x2940
Read of size 1 at addr ffffffff99ab4d20 by task ip/610

CPU: 3 PID: 610 Comm: ip Not tainted 6.8.0-rc7-custom-gd435d6e3e161 #9
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014
Call Trace:
 &lt;TASK&gt;
 dump_stack_lvl+0x8f/0xe0
 print_report+0xcf/0x670
 kasan_report+0xd8/0x110
 __nla_validate_parse+0x1e53/0x2940
 __nla_parse+0x40/0x50
 rtm_del_nexthop+0x1bd/0x400
 rtnetlink_rcv_msg+0x3cc/0xf20
 netlink_rcv_skb+0x170/0x440
 netlink_unicast+0x540/0x820
 netlink_sendmsg+0x8d3/0xdb0
 ____sys_sendmsg+0x31f/0xa60
 ___sys_sendmsg+0x13a/0x1e0
 __sys_sendmsg+0x11c/0x1f0
 do_syscall_64+0xc5/0x1d0
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
[...]

The buggy address belongs to the variable:
 rtm_nh_policy_del+0x20/0x40

Fixes: 2118f9390d83 ("net: nexthop: Adjust netlink policy parsing for a new attribute")
Reported-by: Eric Dumazet &lt;edumazet@google.com&gt;
Closes: https://lore.kernel.org/netdev/CANn89i+UNcG0PJMW5X7gOMunF38ryMh=L1aeZUKH3kL4UdUqag@mail.gmail.com/
Reported-by: syzbot+65bb09a7208ce3d4a633@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/00000000000088981b06133bc07b@google.com/
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://lore.kernel.org/r/20240311162307.545385-4-idosch@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>selftests/net: convert fib_nexthops.sh to run it in unique namespace</title>
<updated>2023-12-15T02:38:35Z</updated>
<author>
<name>Hangbin Liu</name>
<email>liuhangbin@gmail.com</email>
</author>
<published>2023-12-13T06:08:52Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=39333e31672cfc35430d1f5e411188553936b64d'/>
<id>urn:sha1:39333e31672cfc35430d1f5e411188553936b64d</id>
<content type='text'>
Here is the test result after conversion.

 ]# ./fib_nexthops.sh

 Basic functional tests
 ----------------------
 TEST: List with nothing defined                                     [ OK ]
 TEST: Nexthop get on non-existent id                                [ OK ]

 ...

 TEST: IPv6 resilient nexthop group torture test                     [ OK ]

 Tests passed: 234
 Tests failed:   0

Acked-by: David Ahern &lt;dsahern@kernel.org&gt;
Signed-off-by: Hangbin Liu &lt;liuhangbin@gmail.com&gt;
Reviewed-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Tested-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20231213060856.4030084-10-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net</title>
<updated>2023-08-10T21:10:53Z</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2023-08-10T21:04:58Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=4d016ae42efb214d4b441b0654771ddf34c72891'/>
<id>urn:sha1:4d016ae42efb214d4b441b0654771ddf34c72891</id>
<content type='text'>
Cross-merge networking fixes after downstream PR.

No conflicts.

Adjacent changes:

drivers/net/ethernet/intel/igc/igc_main.c
  06b412589eef ("igc: Add lock to safeguard global Qbv variables")
  d3750076d464 ("igc: Add TransmissionOverrun counter")

drivers/net/ethernet/microsoft/mana/mana_en.c
  a7dfeda6fdec ("net: mana: Fix MANA VF unload when hardware is unresponsive")
  a9ca9f9ceff3 ("page_pool: split types and declarations from page_pool.h")
  92272ec4107e ("eth: add missing xdp.h includes in drivers")

net/mptcp/protocol.h
  511b90e39250 ("mptcp: fix disconnect vs accept race")
  b8dc6d6ce931 ("mptcp: fix rcv buffer auto-tuning")

tools/testing/selftests/net/mptcp/mptcp_join.sh
  c8c101ae390a ("selftests: mptcp: join: fix 'implicit EP' test")
  03668c65d153 ("selftests: mptcp: join: rework detailed report")

Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
<entry>
<title>nexthop: Fix infinite nexthop bucket dump when using maximum nexthop ID</title>
<updated>2023-08-09T20:45:12Z</updated>
<author>
<name>Ido Schimmel</name>
<email>idosch@nvidia.com</email>
</author>
<published>2023-08-08T07:52:33Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=8743aeff5bc4dcb5b87b43765f48d5ac3ad7dd9f'/>
<id>urn:sha1:8743aeff5bc4dcb5b87b43765f48d5ac3ad7dd9f</id>
<content type='text'>
A netlink dump callback can return a positive number to signal that more
information needs to be dumped or zero to signal that the dump is
complete. In the second case, the core netlink code will append the
NLMSG_DONE message to the skb in order to indicate to user space that
the dump is complete.

The nexthop bucket dump callback always returns a positive number if
nexthop buckets were filled in the provided skb, even if the dump is
complete. This means that a dump will span at least two recvmsg() calls
as long as nexthop buckets are present. In the last recvmsg() call the
dump callback will not fill in any nexthop buckets because the previous
call indicated that the dump should restart from the last dumped nexthop
ID plus one.

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip nexthop add id 10 group 1 type resilient buckets 2
 # strace -e sendto,recvmsg -s 5 ip nexthop bucket
 sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOPBUCKET, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691396980, nlmsg_pid=0}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 128
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[[{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 128
 id 10 index 0 idle_time 6.66 nhid 1
 id 10 index 1 idle_time 6.66 nhid 1
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 20
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, 0], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
 +++ exited with 0 +++

This behavior is both inefficient and buggy. If the last nexthop to be
dumped had the maximum ID of 0xffffffff, then the dump will restart from
0 (0xffffffff + 1) and never end:

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip nexthop add id $((2**32-1)) group 1 type resilient buckets 2
 # ip nexthop bucket
 id 4294967295 index 0 idle_time 5.55 nhid 1
 id 4294967295 index 1 idle_time 5.55 nhid 1
 id 4294967295 index 0 idle_time 5.55 nhid 1
 id 4294967295 index 1 idle_time 5.55 nhid 1
 [...]

Fix by adjusting the dump callback to return zero when the dump is
complete. After the fix only one recvmsg() call is made and the
NLMSG_DONE message is appended to the RTM_NEWNEXTHOPBUCKET responses:

 # ip link add name dummy1 up type dummy
 # ip nexthop add id 1 dev dummy1
 # ip nexthop add id $((2**32-1)) group 1 type resilient buckets 2
 # strace -e sendto,recvmsg -s 5 ip nexthop bucket
 sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOPBUCKET, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691396737, nlmsg_pid=0}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 148
 recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[[{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, 0]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 148
 id 4294967295 index 0 idle_time 6.61 nhid 1
 id 4294967295 index 1 idle_time 6.61 nhid 1
 +++ exited with 0 +++

Note that if the NLMSG_DONE message cannot be appended because of size
limitations, then another recvmsg() will be needed, but the core netlink
code will not invoke the dump callback and simply reply with a
NLMSG_DONE message since it knows that the callback previously returned
zero.

Add a test that fails before the fix:

 # ./fib_nexthops.sh -t basic_res
 [...]
 TEST: Maximum nexthop ID dump                                       [FAIL]
 [...]

And passes after it:

 # ./fib_nexthops.sh -t basic_res
 [...]
 TEST: Maximum nexthop ID dump                                       [ OK ]
 [...]

Fixes: 8a1bbabb034d ("nexthop: Add netlink handlers for bucket dump")
Signed-off-by: Ido Schimmel &lt;idosch@nvidia.com&gt;
Reviewed-by: Petr Machata &lt;petrm@nvidia.com&gt;
Reviewed-by: David Ahern &lt;dsahern@kernel.org&gt;
Link: https://lore.kernel.org/r/20230808075233.3337922-4-idosch@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
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